/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/types.h>
#include <sys/archsystm.h>
#include <sys/machsystm.h>
#include <sys/sunndi.h>
#include <sys/sunddi.h>
#include <sys/ddi_subrdefs.h>
#include <sys/xpv_support.h>
#include <sys/xen_errno.h>
#include <sys/hypervisor.h>
#include <sys/gnttab.h>
#include <sys/xenbus_comms.h>
#include <sys/xenbus_impl.h>
#include <sys/sysmacros.h>
#include <sys/x86_archext.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/conf.h>
#include <sys/devops.h>
#include <sys/pc_mmu.h>
#include <sys/cmn_err.h>
#include <sys/cpr.h>
#include <sys/ddi.h>
#include <vm/seg_kmem.h>
#include <vm/as.h>
#include <vm/hat_pte.h>
#include <vm/hat_i86.h>

static int xen_hvm_inited;

/*
 * This structure is ordinarily constructed by Xen. In the HVM world, we
 * manually fill in the few fields the PV drivers need.
 */
static start_info_t __xen_info;
start_info_t *xen_info = NULL;

static int xen_bits = -1;
static int xen_major = -1, xen_minor = -1;

/*
 * Feature bits; more bits will be added, like direct I/O, etc.
 */
#define XEN_HVM_HYPERCALLS      0x0001
#define XEN_HVM_TLBFLUSH        0x0002
static uint64_t xen_hvm_features;

/* Metadata page shared between domain and Xen */
shared_info_t *HYPERVISOR_shared_info = NULL;
pfn_t xen_shared_info_frame;

/* Page containing code to issue hypercalls.  */
extern caddr_t hypercall_page;
extern caddr_t hypercall_shared_info_page;

static int
hvm_get_param(int param_id, uint64_t *val)
{
        struct xen_hvm_param xhp;

        xhp.domid = DOMID_SELF;
        xhp.index = param_id;
        if ((HYPERVISOR_hvm_op(HVMOP_get_param, &xhp) < 0))
                return (-1);
        *val = xhp.value;
        return (0);
}

void
xen_hvm_init(void)
{
        struct cpuid_regs cp;
        uint32_t xen_signature[4], base;
        char *xen_str;
        struct xen_add_to_physmap xatp;
        xen_capabilities_info_t caps;
        pfn_t pfn;
        uint64_t msrval, val;

        if (xen_hvm_inited != 0)
                return;

        xen_hvm_inited = 1;

        /*
         * Xen's pseudo-cpuid function returns a string representing
         * the Xen signature in %ebx, %ecx, and %edx.
         * Loop over the base values, since it may be different if
         * the hypervisor has hyper-v emulation switched on.
         *
         * %eax contains the maximum supported cpuid function.
         */
        for (base = 0x40000000; base < 0x40010000; base += 0x100) {
                cp.cp_eax = base;
                (void) __cpuid_insn(&cp);
                xen_signature[0] = cp.cp_ebx;
                xen_signature[1] = cp.cp_ecx;
                xen_signature[2] = cp.cp_edx;
                xen_signature[3] = 0;
                xen_str = (char *)xen_signature;
                if (strcmp("XenVMMXenVMM", xen_str)  == 0 &&
                    cp.cp_eax >= (base + 2))
                        break;
        }
        if (base >= 0x40010000)
                return;

        /*
         * cpuid function at base + 1 returns the Xen version in %eax.  The
         * top 16 bits are the major version, the bottom 16 are the minor
         * version.
         */
        cp.cp_eax = base + 1;
        (void) __cpuid_insn(&cp);
        xen_major = cp.cp_eax >> 16;
        xen_minor = cp.cp_eax & 0xffff;

        /*
         * Below version 3.1 we can't do anything special as a HVM domain;
         * the PV drivers don't work, many hypercalls are not available,
         * etc.
         */
        if (xen_major < 3 || (xen_major == 3 && xen_minor < 1))
                return;

        /*
         * cpuid function at base + 2 returns information about the
         * hypercall page.  %eax nominally contains the number of pages
         * with hypercall code, but according to the Xen guys, "I'll
         * guarantee that remains one forever more, so you can just
         * allocate a single page and get quite upset if you ever see CPUID
         * return more than one page."  %ebx contains an MSR we use to ask
         * Xen to remap each page at a specific pfn.
         */
        cp.cp_eax = base + 2;
        (void) __cpuid_insn(&cp);

        /*
         * Let Xen know where we want the hypercall page mapped.  We
         * already have a page allocated in the .text section to simplify
         * the wrapper code.
         */
        pfn = va_to_pfn(&hypercall_page);
        msrval = mmu_ptob(pfn);
        wrmsr(cp.cp_ebx, msrval);

        /* Fill in the xen_info data */
        xen_info = &__xen_info;
        (void) sprintf(xen_info->magic, "xen-%d.%d", xen_major, xen_minor);

        if (hvm_get_param(HVM_PARAM_STORE_PFN, &val) < 0)
                return;
        /*
         * The first hypercall worked, so mark hypercalls as working.
         */
        xen_hvm_features |= XEN_HVM_HYPERCALLS;

        xen_info->store_mfn = (mfn_t)val;
        if (hvm_get_param(HVM_PARAM_STORE_EVTCHN, &val) < 0)
                return;
        xen_info->store_evtchn = (mfn_t)val;

        /* Figure out whether the hypervisor is 32-bit or 64-bit.  */
        if ((HYPERVISOR_xen_version(XENVER_capabilities, &caps) == 0)) {
                ((char *)(caps))[sizeof (caps) - 1] = '\0';
                if (strstr(caps, "x86_64") != NULL)
                        xen_bits = 64;
                else if (strstr(caps, "x86_32") != NULL)
                        xen_bits = 32;
        }

        if (xen_bits < 0)
                return;
        ASSERT(xen_bits == 64);

        /*
         * Allocate space for the shared_info page and tell Xen where it
         * is.
         */
        xen_shared_info_frame = va_to_pfn(&hypercall_shared_info_page);
        xatp.domid = DOMID_SELF;
        xatp.idx = 0;
        xatp.space = XENMAPSPACE_shared_info;
        xatp.gpfn = xen_shared_info_frame;
        if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp) != 0)
                return;

        HYPERVISOR_shared_info = (void *)&hypercall_shared_info_page;

        /*
         * A working HVM tlb flush hypercall was introduced in Xen 3.3.
         */
        if (xen_major > 3 || (xen_major == 3 && xen_minor >= 3))
                xen_hvm_features |= XEN_HVM_TLBFLUSH;
}

/*
 * Returns:
 *          -1 if a feature is not available
 *          1 if a boolean feature is available
 *          > 0 if numeric feature is available
 */
int
xpv_feature(int which)
{
        switch (which) {
        case XPVF_BITS:
                return (xen_bits);
        case XPVF_VERSION_MAJOR:
                return (xen_major);
        case XPVF_VERSION_MINOR:
                return (xen_minor);
        case XPVF_HYPERCALLS:
                if (xen_hvm_features & XEN_HVM_HYPERCALLS)
                        return (1);
                break;
        case XPVF_SHARED_INFO:
                if (HYPERVISOR_shared_info != NULL)
                        return (1);
                break;
        case XPVF_TLB_FLUSH:
                if (xen_hvm_features & XEN_HVM_TLBFLUSH)
                        return (1);
                break;
        default:
                break;
        }

        return (-1);
}